You don't need jQuery, just use javascript's Math.random
function.
edit: If you want to have a number from 1 to 6 show randomly every second, you can do something like this:
<span id="number"></span>
<script language="javascript">
function generate() {
$('#number').text(Math.floor(Math.random() * 6) + 1);
}
setInterval(generate, 1000);
</script>